Fumigation toxicity of monoterpenoids to several stored product insects

Twenty naturally occurring monoterpenoids were evaluated in a preliminary fumigation screening test on some important stored-product pest insects, including the rice weevil, Sitophilus oryzae, the red flour beetle, Tribolium castaneum, the sawtoothed grain beetle, Oryzaephilus surinamensis, the house fly, Musca domestica, and the German cockroach, Blattella germanica. Cineole, l-fenchone, and pulegone at 50 μg/ml air caused 100% mortality in all five species tested. Ketone compounds were generally more toxic than other monoterpenoids. Three monoterpenoids, the ketones pulegone, l-fenchone, and the aldehyde perillaldehyde, were selected for further study. They were effective against T. castaneum in the fumigation assay; however the toxicity was relatively low in comparison to dichlorvos. LC₅₀ values of these three monoterpenoids tended to decrease at longer exposure times and higher temperatures. Inclusion of either maize kernels or house fly medium (HFM) increased LC₅₀ values, HFM more so than maize kernels. Monoterpenoids may be suitable as fumigants or vapor-phase insecticides because of their high volatility, fumigation efficacy, and their safety.     

Corcyra cephalonica: A serious pest of stored products or a factitious host of biocontrol agents?

The rice moth, Corcyra cephalonica, is an economically significant stored product pest (SPP). It is widely distributed and causes severe damage to grains and products in storage under varying environmental conditions. However, compared to other Lepidopterous pests like Ephestia kuehniella and Plodia interpunctella, the pest potential of C. cephalonica is often underestimated. While farmers typically rely on chemical control to manage insect pests, recent studies suggest that non-chemical control methods can be used successfully as alternatives for their management. Therefore, in-depth knowledge of rice moth biology and its current pest status is essential for developing integrated management systems. Besides being a pest under natural conditions, Corcyra cephalonica also serves as a factitious host of natural enemies. It has a short life cycle and can be easily mass-reared on a variety of feeding media, making it a preferable alternative host with year-round availability, which can help in the cost-effective production of beneficial insects such as biocontrol agents and, as a result, in better management of other harmful agricultural insect pests. In the second part of this review, we examine the suitability of the rice moth as a laboratory host and conclude by determining whether Corcyra is best addressed as a serious pest of stored products or as a factitious host of biocontrol agents.     

粮堆磷化氢浓度衰减阶段数学模型及验证研究

研究了压力半衰期为158 s的高大平房仓中磷化氢熏蒸后的浓度变化规律,建立了粮堆内磷化氢浓度和熏蒸时间的关系模型。经压力半衰期分别为105、96、69 s的三个高大平房仓磷化氢浓度变化的实仓验证,表明粮堆内磷化氢浓度衰减阶段的浓度呈指数下降趋势,磷化氢浓度衰减阶段浓度和时间符合指数模型C=ae~(-bt)(a0;b0)(其中C为磷化氢浓度,m L/m~3;t为熏蒸时间,d;e为自然指数;a、b为常数)。该模型可用于计算不同磷化氢浓度对应的熏蒸时间、不同熏蒸时间对应的磷化氢浓度、预测粮堆的补药时间等。结合气体发生阶段模型还可以计算磷化氢熏蒸最大浓度、最低熏蒸浓度下的有效熏蒸时间以及磷化氢浓度半数衰减时间HLT。     

Genetic diversity and its geographic structure in Sitophilus oryzae (Coleoptera; Curculionidae) across India – implications for managing phosphine resistance

The rice weevil, Sitophilus oryzae, is a serious global pest of stored grains. Fumigation with phosphine gas is the primary control method for S. oryzae, but the indiscriminate and prolonged use of phosphine gas has led to the development of heritable resistance. Developing and implementing an effective phosphine resistance management strategy for S. oryzae relies on an understanding of its genetic diversity and any structuring of that diversity geographically. We therefore sequenced the mitochondrial cytochrome c oxidase subunit I gene from 143 S. oryzae specimens collected from 37 locations across India, and from that assessed the genetic diversity of the species and its phylogeographic structuring. In addition, we compared the genetic diversity in Indian S. oryzae populations (the hypothesised origin of this beetle) to global populations. Genetic diversity was low in Indian S. oryzae, with only eight haplotypes (including two very common haplotypes) identified. The low level of mitochondrial diversity observed in this species appears typical of stored product pests, perhaps suggesting that low mitochondrial diversity is associated with repeated phosphine fumigations, which may eliminate low frequency haplotypes. The genetic diversity of S. oryzae in India is, however, higher than in many other countries, though comparable levels were identified in China. There was no evidence of population genetic structure across India, with most haplotypes found in three of the broad biogeographic regions. This lack of phylogeographic structuring indicates significant gene-flow across India, most likely through the incidental anthropogenic transport of this relatively poor (or reluctant) flyer. The major practical implication is that phosphine resistance management for S. oryzae needs to be dealt with country wide, as populations are not isolated.     

二氧化氯处理对冬枣保鲜的影响研究

探讨了二氧化氯(ClO)2在冬枣保鲜上的应用,研究了二氧化氯处理对冬枣好果率、果实硬度、可溶性果胶、PG酶活性、Vc及PPO酶活性的影响。试验结果表明:二氧化氯有利于冬枣保鲜,对提高贮藏冬枣的商品品质和营养价值有一定的积极作用,二氧化氯用于冬枣贮藏保鲜最佳质量分数为80mg/kg。经二氧化氯处理的冬枣在贮藏80d后,其好果率、果实硬度、Vc、PG酶活性均高于对照组;可溶性果胶、PPO酶活性均低于对照组。     

Toxicity of essential oils from plants towards Tyrophagus putrescentiae (Schrank) and Suidasia pontifica Oudemans (Acari: Astigmata)

The fumigant activity of essential oils from Cinnamomum zeylanicum, Eugenia uniflora, Eugenia uvalha, Melaleuca leucadendra, Piper marginatum, and Schinus terebinthifolius was evaluated for control of the mites Tyrophagus putrescentiae (Schrank) and Suidasia pontifica Oudemans. The average mortality, after 24 h of exposure to oil of C. zeylanicum at the highest concentration tested (50 μL/L of air), was 97.7 and 92.9% for T. putrescentiae and S. pontifica, respectively. Mortality of the two species at the same concentration of S. terebinthifolius was 86.7 and 100%, respectively. As measured by LC₅₀, the most toxic oil for T. putrescentiae was eugenol (0.23 μL/L air) followed by C. zeylanicum (0.82 μL/L air), E. uvalha (3.71 μL/L air), and S. terebinthifolius (8.25 μL/L air). The most toxic oil for S. pontifica was eugenol (0.57 μL/L air) followed by C. zeylanicum (1.75 μL/L air), S. terebinthifolius (4.87 μL/L air), and E. uvalha (11.09 μL/L air). Both mite species responded faster to S. terebinthifolius than to the other essential oils.     

A novel use of modified atmospheres: Storage insect population control

The research described here aimed to establish the feasibility of using modified atmospheres (MA) to protect commodities throughout their storage life by using oxygen (O₂) levels that disrupt the life cycles of the target beetle species. Rather than achieving complete mortality of all stages, the aim was to identify more easily obtainable MAs that would kill the most susceptible stage and prevent population growth. Simulated burner gas and nitrogen (N₂) atmospheres with O₂ contents between 3% and 6%, were tested, along with a N₂-based MA with elevated carbon dioxide (CO₂) (10–20%).

Laboratory tests were carried out on five species of stored-product beetles, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Sitophilus granarius, S. oryzae and Tribolium castaneum. After exposure to the MAs for 28 d an assessment was made of the mortality of adults, the number of adults from progeny produced under the MAs and, for the simulated burner gas, the number of adults from progeny produced in a 28-d period after exposure to the MA. The tests were carried out at 20 and 25 °C with 75% and 85% r.h. at each temperature.

The O₂ content preventing population growth varied with species and temperature. For simulated burner gas or N₂ it was about 4% for O. surinamensis, S. granarius and S. oryzae, and about 3% for C. ferrugineus and T. castaneum at 25 °C. At 20 °C it was about 3% for all species tested. When CO₂ was increased to 10% or 20%, reducing O₂ to 5% was sufficient to eliminate emergence of S. granarius at 20°C, but a few individuals emerged at 25 °C. For C. ferrugineus there was a 95% reduction with 5% O₂ plus 20% CO₂ at 20 °C, but not at 25 °C.     

1-甲基环丙烯结合茉莉酸甲酯雾化熏蒸对石榴采后品质的影响

目的 探究1-甲基环丙烯(1-methylcycloproene,1-MCP)和茉莉酸甲酯(methyl jasmonate,MeJA)联合处理对石榴贮藏过程生理代谢和病害的协同调控作用。方法 以和田石榴为对象,采用1-MCP结合MeJA雾化熏蒸处理,研究其对冷藏条件下果实品质的影响。结果 1-MCP结合MeJA雾化熏蒸处理有效延缓了石榴果实在冷藏过程中的果皮褐变,较好保持了果实色泽,降低了果实腐烂率,保持了果实可溶性固形物、可滴定酸和总酚含量,抑制多酚氧化酶活性,减缓过氧化物酶、过氧化氢酶和超氧化物歧化酶活性的下降,同时保持较低的丙二醛含量和细胞膜透性。此外,结合处理还能维持较高的果实可溶性蛋白含量并保持良好的果皮微观结构。结论 1-MCP结合100μmol/L MeJA雾化熏蒸处理的石榴贮藏品质最佳,为石榴采后商品化处理提供了依据。     

Insect infestation in stored animal products

Published information about insect pest infestation in dried or preserved animal products comprising food items like dried fish and milk powder and non-food materials such as hides and skins, silkworm cocoons, wool and woollen materials, honeybee combs, fishmeal and museum collections/exhibits and control measures has been summarised in this review. Beetle and moth pests belonging to the Dermestidae and Tineidae, respectively, attack the animal products, during the processing or manufacturing stage as well as in storage. The insects cause considerable loss or damage to the commodity in terms of quantity, quality and market value. Silk, apiculture and leather industries are particularly affected by the pests. Data on the extent of losses due to insect pests in various preserved animal products are lacking. Insect control measures in these products differ depending on the conditions of storage or processing and the relevant cost factor. Phosphine fumigation plays an important role in insect pest elimination in the majority of the stored animal products. For disinfesting museum objects and honeycombs, freezing (for artefacts) or modified atmosphere application of CO₂ or nitrogen is preferred. Commodities such as woollen materials, dried fish, fishmeal and feeds containing animal products and their storage premises are sometimes treated with residual contact insecticides such as deltamethrin, pirimiphos-methyl, permethrin and synergised pyrethrins. For protecting animal products, especially dried fish, different countries have examined alternatives including plant extracts and vegetable oils.The need for detailed studies on (i) fumigation with alternatives to methyl bromide such as sulphuryl fluoride, ethyl formate and ozone, (ii) disinfestation methods involving the active principles from natural products and (iii) exploitation of insect traps for pest management in museums has been highlighted.     

二氧化氯杀菌剂在甘蔗糖厂的应用研究

采用二氧化氯对甘蔗及压榨过程蔗料、蔗汁进行杀菌,研究二氧化氯对甘蔗及压榨过程的杀菌效果。结果表明:使用二氧化氯对甘蔗原料进行杀菌,处理甘蔗蔗汁纯度较未处理的高0.2 GP以上;在压榨过程使用二氧化氯,杀菌率平均达到96.39%,初混汁纯度差值平均小于0.8GP,表明在二氧化氯作用下,绝大多数微生物被杀灭,因此蔗糖无形损失减少。     

二氧化氯(ClO2)对葡萄表面大肠杆菌杀灭效果的研究

用CiO2溶液浸泡已接种大肠杆菌的葡萄,观察处理时间、ClO2溶液体积与葡萄质量之比(v/m)、ClO2浓度对杀菌效果的影响.结果表明:处理时间从5min延长到10min杀菌效果上升2.35±0.18log,但进一步延长处理时间上升趋势变缓;v/m为2时的杀菌效果低于其为3、4、5时的杀菌效果,后3者之间无显著性差异(P＞0.05);ClO2浓度在很大程度上影响着杀菌效果,ClO2浓度增加杀菌效果明显提高.